Render GLSL Shaders in LWJGL

LWJGLMain.java

package net.superblaubeere27.glslsandboxrenderer;

import org.lwjgl.*;
import org.lwjgl.glfw.*;
import org.lwjgl.opengl.*;
import org.lwjgl.system.*;

import java.io.IOException;
import java.nio.*;

import static org.lwjgl.glfw.Callbacks.*;
import static org.lwjgl.glfw.GLFW.*;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.opengl.GL20.glUseProgram;
import static org.lwjgl.system.MemoryStack.*;
import static org.lwjgl.system.MemoryUtil.*;

public class LWJGLMain {

    // The window handle
    private long window;
    private GLSLSandboxShader glslShader;

    public void run() {
        System.out.println("Starting with LWJGL " + Version.getVersion() + ".");

        init();
        loop();

        // Free the window callbacks and destroy the window
        glfwFreeCallbacks(window);
        glfwDestroyWindow(window);

        // Terminate GLFW and free the error callback
        glfwTerminate();
        glfwSetErrorCallback(null).free();
    }

    private void init() {
        // Setup an error callback. The default implementation
        // will print the error message in System.err.
        GLFWErrorCallback.createPrint(System.err).set();

        // Initialize GLFW. Most GLFW functions will not work before doing this.
        if ( !glfwInit() )
            throw new IllegalStateException("Unable to initialize GLFW");

        // Configure GLFW
        glfwDefaultWindowHints(); // optional, the current window hints are already the default
        glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE); // the window will stay hidden after creation
        glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE); // the window will be resizable

        // Create the window
        window = glfwCreateWindow(1280, 720, "Hello World!", NULL, NULL);
        if ( window == NULL )
            throw new RuntimeException("Failed to create the GLFW window");

        // Setup a key callback. It will be called every time a key is pressed, repeated or released.
        glfwSetKeyCallback(window, (window, key, scancode, action, mods) -> {
            if ( key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE )
                glfwSetWindowShouldClose(window, true); // We will detect this in the rendering loop
        });

        // Get the thread stack and push a new frame
        try ( MemoryStack stack = stackPush() ) {
            IntBuffer pWidth = stack.mallocInt(1); // int*
            IntBuffer pHeight = stack.mallocInt(1); // int*

            // Get the window size passed to glfwCreateWindow
            glfwGetWindowSize(window, pWidth, pHeight);

            // Get the resolution of the primary monitor
            GLFWVidMode vidmode = glfwGetVideoMode(glfwGetPrimaryMonitor());

            // Center the window
            glfwSetWindowPos(
                    window,
                    (vidmode.width() - pWidth.get(0)) / 2,
                    (vidmode.height() - pHeight.get(0)) / 2
            );
        } // the stack frame is popped automatically

        // Make the OpenGL context current
        glfwMakeContextCurrent(window);
        // Enable v-sync
        glfwSwapInterval(1);

        // Enable platform-specific features like shaders
        GL.createCapabilities();

        try {
            this.glslShader = new GLSLSandboxShader("/noise.fsh");
        } catch (IOException e) {
            // End execution
            throw new IllegalStateException(e);
        }

        // Make the window visible
        glfwShowWindow(window);
    }

    private void loop() {
        long startTime = System.currentTimeMillis();

        // Set the clear color
        glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

        glColor4f(1.0f, 1.0f, 1.0f, 1.0f);

        // Run the rendering loop until the user has attempted to close
        // the window or has pressed the ESCAPE key.
        while ( !glfwWindowShouldClose(window) ) {
            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear the framebuffer

            int width;
            int height;
            
            float mouseX;
            float mouseY;
            
            try ( MemoryStack stack = stackPush() ) {
                IntBuffer pWidth = stack.mallocInt(1); // int*
                IntBuffer pHeight = stack.mallocInt(1); // int*
                DoubleBuffer pMouseX = stack.mallocDouble(1); // int*
                DoubleBuffer pMouseY = stack.mallocDouble(1); // int*

                // Get the window size passed to glfwCreateWindow
                glfwGetWindowSize(window, pWidth, pHeight);
                glfwGetCursorPos(this.window, pMouseX, pMouseY);

                width = pWidth.get(0);
                height = pHeight.get(0);

                mouseX = (float) pMouseX.get(0);
                mouseY = (float) pMouseY.get(0);
            }
            
            this.glslShader.useShader(width, height, mouseX, mouseY, (System.currentTimeMillis() - startTime) / 1000f);

            // Apply the shader to the whole screen
            glBegin(GL_QUADS);

            glVertex2f(-1f, -1f);
            glVertex2f(-1f, 1f);
            glVertex2f(1f, 1f);
            glVertex2f(1f, -1f);

            glEnd();
            
            glUseProgram(0);

            glfwSwapBuffers(window); // swap the color buffers

            // Poll for window events. The key callback above will only be
            // invoked during this call.
            glfwPollEvents();
        }
    }

    public static void main(String[] args) {
        new LWJGLMain().run();
    }

}